Sudden Death Syndrome lives up to its name. Angie Peltier, University of Illinois, explains the soil pathogens that cause SDS infect the roots, then produces toxins that are translocated up causing the first noticeable symptom: ‘yellow flecking’ on leaves. The yellowing spreads and eventually turns the once green tissue brown, until the only green left on the leaves is the main vein. “Then the leaflets fall off,” Peltier says. “The years we have leaf drop early on can have a significant impact on yield.”
The challenge is managing SDS. You don’t manage it, you prevent it. In fields with a history of disease, Peltier recommends selecting soybean varieties with genetic resistance to SDS and considering the seed treatment ILeVO.
“ILeVO is a remarkable seed treatment, there’s never been a technology like this available to growers. It’s an important tool,” says Kerry Grossweiler, Bayer CropScience seed growth equipment and coatings manager. “Treat soybeans in April, plant them in May and you’ll see a positive impact in August or September.”
Peltier and Grossweiler both noted how widespread SDS was in 2014 and 2015. “We’ve seen it in southern Illinois, and across central and northern Illinois,” Grossweiler says. “It’s everywhere.”
That’s why researchers have looked into several management options.
Peltier explains several tactics, such as crop rotation, tillage, planting dates, have all been tested. Unfortunately, rotating away from corn and soybeans doesn’t fit into most cropping plans in Illinois. Tillage had minimal effects on SDS. And changing planting dates just for SDS control is not something Peltier recommends. As for chemical control, “There’s little chance foliar fungicide will come into contact with the pathogen at the time of infection,” Peltier says.
That leaves proactive measures, such as SDS resistant varieties and ILeVO. In research trials, ILeVO reduced SDS symptoms by 5% and resulted in a 3 bu/A yield response. “But it’s not bullet proof,” Peltier says. “Even ILeVO has its limits. With really, really high levels of disease, you’ll get a yield response, but it’s not magic.”
ILeVO may not be magic, but it does provide one effective way to protect soybeans from this devastating disease. And as the saying goes, the best offense is a good defense.